Immunohistochemical PGP 9.5 positivity in human osteoblasts may indicate that compensatory and dysplastic craniofacial growth are under control by peripheral nerves.
OBJECTIVE
The purpose was to examine human osteoblasts immunohistochemically in order to clarify the significance of the innervation for alveolar bone growth.


METHODS
Unstained sections available from 21 normal human mandibles (foetal gestational ages: 14-22 weeks).


METHODS
Before sectioning in 1980-1990, the mandibular tissue had been fixed in 4% neutral-buffered formaldehyde for 5 days. Tissue blocks were then decalcified in equal parts of 2% citric acid and 20% sodium citrate for 7-15 days, dehydrated, embedded in paraffin, and sagittally cut into 4-mum-thick serial sections and mounted on Superfrost Plus microscope slides. Sections were dried overnight at 40 degrees C. In the present study, paraffin sections were deparaffinized and treated with Tris-EDTA (Merck, Germany), pH 9.0, and immunohistochemically tested with polyclonal rabbit anti-PGP 9.5, and the EnVision +/HRP dual link (K4065; DAKO Denmark A/S, Denmark) method.


RESULTS
A pronounced protein gene product (PGP) 9.5 activity was registered in osteoblasts from alveolar bone in all specimens. In all cases, the activity was intense at the top of and labially to the alveolar bone, while less or no activity was observed on the inner lingual aspects of the alveolar processes. Osteoclasts and osteocytes reacted vaguely or negatively.


CONCLUSIONS
As the present study has demonstrated that human osteoblast activity in the alveolar bone seemingly responds to innervation, it is suggested that the peripheral nervous system via the trigeminal ganglion regulates compensatory and dysplastic alveolar bone formation.
Kjaer
I
I
Department of Orthodontics, School of Dentistry, University of Copenhagen, Copenhagen, Denmark. ik@odont.ku.dk
Nolting
D
D
D000539:Alveolar Process / Q000737:chemistry / Q000196:embryology* / Q000294:innervation*; D047109:Fetal Development; D006801:Humans; D007124:Immunoenzyme Techniques; D008334:Mandible / Q000196:embryology*; D008445:Maxillofacial Development / Q000502:physiology; D010006:Osteoblasts / Q000737:chemistry* / Q000502:physiology; D012668:Trigeminal Ganglion / Q000502:physiology; D043222:Ubiquitin Thiolesterase / Q000032:analysis* / Q000502:physiology
C482860:UCHL1 protein, human; D043222:Ubiquitin Thiolesterase